Radical rebel groups have handed over the body of a slain Syrian pilot they had killed earlier to the the Syrian authorities, a monitor group reported on Sunday.

The body of Lt. Col. Nawras al-Hasan, who had been executed by the rebels when he parachuted his crashing warplane over a rebel-held areas east of Damascus last week, was delivered to the Syrian authorities, said the Syrian Observatory for Human Rights.

Al-Hasan was executed by rebels from the al-Qaida-linked Nusra Front in the town of Jairud in the eastern countryside of Damascus.

The state news agency SANA said al-Hassan was on a training mission when his plane malfunctioned and crashed, after he ejected himself.

However, the rebels said they downed the plane.

On Saturday, the Observatory, which relies on a network of activists on ground, said the Syrian air force carried out intense airstrikes and shelling on Jairud, killing 43 people, and injuring tens of others, some in critical conditions.

The shelling of Jairud appeared to be a retaliation for the slain pilot.

On Sunday, the Observatory said there is information that the rebels of the Nusra Front and likeminded militant groups were evacuating their posts in Jairud, following the intense shelling.